Paper guide rope

ABSTRACT

The invention relates to a paper guide rope ( 1 ) braided from a plurality of textile subunits ( 2, 2′, 2 ″), wherein each subunit contains a plurality of twisted yarns ( 3 ) made from multifilament yarn. The rope according to the invention is characterized in that the titre of at least part of the twisted yarns, preferably of all the twisted yarns, is in each case at most 5000 dtex, and that the twist rate of at least part of the twisted yarns, preferably of all the twisted yarns, is in each case at least 150 T/m.

The present invention relates to a paper guide rope which is braidedfrom a plurality of textile subunits.

Paper guide ropes serve for guiding the paper web, which is beinggenerated, through the roller system in the various sections (e.g.,dryer section, size presses, take-up stand) of the paper-making machine.For this purpose, two or three paper guide ropes normally run closelynext to each other, and the so-called paper tip is clamped between thoseropes and is thus guided through the sections in a controlled manner.The paper guide ropes are circulated, i.e., the ends of a rope arespliced into each other so that a rope ring emerges the length of whichdepends on the section of the paper-making machine, but usually has anorder of magnitude from 50 to 100 m.

Paper guide ropes typically have a diameter ranging from 6 to 17 mm.Their fundamental properties result from the application: the adhesionor clamping force, respectively, between the rope and the paper must bestrong enough for the feeding of the paper tip to be possible. Becauseof the length of the rope ring, the elongation of the rope must not behigh. The breaking resistances play a minor part, the lifetime under theunfavourable conditions of a paper-making machine is crucial, however.

The lifetime of paper guide ropes in paper-making machines is limited.Depending on the section (i.e., the application site) in thepaper-making machine, the lifetime of a rope is longer or shorter. Theropes are exposed to various influences such as heat, moisture,chemicals and in particular abrasion locations. Particularly problematicsections are the size presses, where chemicals deposit on the ropepulleys and the paper guide ropes come into contact with incrustationsforming in this way, hence are exposed to a particularly strongabrasion.

There have already been different approaches to prolong the lifetime ofpaper guide ropes via their construction.

In EP 0 150 702 A, a so-called “reinforcement” of the rope withmonofilaments is suggested. A “reinforcement” is understood to be awrapping, braiding, knitting etc. around the rope or the fibre materialused for manufacturing the rope or subunits of the rope, respectively,which have been made of said fibre material, with the surface of thefibre material, the rope or the subunit, respectively, not being coveredcompletely, however.

In WO 06/55995 A as well as in AT 503.289 B, further details ofreinforcements for paper guide ropes are described.

From US 2005/0204909, paper guide ropes are known in which, at first, amonofilament is twisted around a twisted multifilament yarn, i.e., areinforcement is produced on the twisted multifilament yarn. Thereinforced twisted multifilament yarn is then braided into small ropesfrom which, in turn, the paper guide rope is braided. Alternatively, US2005/0204909 describes the manufacture of a rope in which thereinforcement (the circumferential twisting with a monofilament) is notattached to the original twisted multifilament yarn, but to the smallropes which have been braided from said twisted yarn.

All those suggestions have in common that a reinforcement is applied tothe rope or to one of its elements (the original twisted yarn, a subunitproduced from the twisted yarn such as a small rope).

Monofilaments used for the production of reinforcements have thecharacteristic of breaking soon during use and of rendering the ropeshabby. Apparently, the rope looks worn, although it absolutely couldstill have a long lifetime. However, in paper-making machines, the ropesare normally assessed for their appearance, and a replacement is decidedupon according to their appearance.

A further important characteristic of paper guide ropes is theirelongation. During their use, the ropes have to be tensed and mustremain so. If a paper guide rope stretches, this change of length iscompensated for by means of a tension station so that the tension of therope remains the same. Normally, the tension path of the tension stationis limited, however. Thus, an elongation of the rope which is too strongwill have the effect that it can no longer be tensed, will thus beexposed to increased wear and may also bounce out of its track and musttherefore be replaced. Known ropes comprising a reinforcement made ofmonofilaments exhibit a comparatively high elongation, which is causedby the construction.

From CZ 19446 U1, a rope is known which is braided from a plurality oftextile subunits, each consisting of yarns which merely lie next to eachother. The yarns are thereby not twsited. As a result, a rope withcomparatively little elongation is formed.

It is the object of the present invention to provide a paper guide ropewhich has a substantially higher abrasion resistance than conventionalpaper guide ropes and, at the same time, an elongation which issufficiently minor. In particular, the paper guide rope should notcomprise a reinforcement for the above-described reasons.

Said object is achieved by means of a paper guide rope braided from aplurality of textile subunits, wherein each subunit contains a pluralityof twisted yarns made from multifilament yarn, and which ischaracterized in that the titre of at least part of the twisted yarns,preferably of all the twisted yarns, is in each case at most 5000 dtex,and that the twist rate of at least part of the twisted yarns,preferably of all the twisted yarns, is in each case at least 150 T/m.

SHORT DESCRIPTION OF THE FIGURES

FIG. 1 shows an embodiment of a braided paper guide rope.

FIG. 2 shows a further embodiment of a braided paper guide rope.

DETAILED DESCRIPTION OF THE INVENTION

It has been found that paper guide ropes the textile subunits of whichare not made up of thick twisted yarns (having a thickness of, e.g.,8400 dtex per twisted yarn) with a relatively low twist rate (typicallyabout 80 T/m), but of relatively thin twisted yarns with a very hightwist rate, exhibit excellent properties in terms of abrasionresistance, with the elongation properties being good at the same time.

With the rope according to the invention, there is no necessity inparticular to provide an additional reinforcement so that, according toa preferred embodiment of the present invention, neither the rope northe subunits or their twisted yarns, respectively, comprise areinforcement.

The twist rate of the twisted yarns in the rope according to theinvention may in each case be 150 T/m to 350 T/m, preferably 150 T/m to250 T/m, particularly preferably 200 T/m.

The titre of the twisted yarns in the rope according to the inventionmay in each case be 400 dtex to 5000 dtex, preferably 2500 dtex to 4500dtex, particularly preferably 4200 dtex.

Any suitable textile multifilament yarn may be used as a fibre materialfor manufacturing the twisted yarns. In particular, at least part of thetwisted yarns may consist of polyamide multifilament yarn. However, yarnmixtures may also be provided. For example, a twisted yarn with 3strands can be composed of one yarn of polyamide and two yarns of adifferent material, for example, polyester.

Optionally, the multifilament yarns and, respectively, the twisted yarnsproduced therefrom can be impregnated and/or thermoset in a manner knownper se. Also the entire rope can be impregnated and/or thermoset in amanner known per se.

The number of twisted yarns per subunit is preferably at least 7,particularly preferably 9 to 16.

For the purposes of the present invention, the term “subunit” isunderstood to mean accumulations of fibre material which end up lying inparallel and next to each other in the rope, such as, e.g., a pluralityof twisted yarns lying next to each other, twisted yarns which have beenbraided or twisted yarns which have been twisted around each other.

In order to demonstrate the term “subunit”, FIGS. 1 and 2 show twodifferent embodiments of a paper guide rope 1.

In the embodiment according to FIG. 1, the rope 1 is composed ofsubunits 2 (herein: braided rhombi) which, in each case, contain morethan seven twisted yarns 3. Said subunits 2 can be produced, in eachcase, by means of two bobbins operating one after the other, with theshape of a braided rhombus resulting therefrom (framed in FIG. 1). Inthe subunits, the twisted yarns lie essentially in parallel next to eachother.

In the embodiment according to FIG. 2, the rope 1 is likewise composedof subunits 2, which, in each case, are produced by means of twobobbins. The result is, in each case, two elements 2′, 2″ (framed inFIG. 2), which lie next to each other at least partly. The subunit 2made up of the sections lying next to each other of the two elements 2′,2″ again comprises at least seven twisted yarns. Also in thisembodiment, the twisted yarns lie essentially next to each other in thesubunits 2 or in their elements 2′, 2″, respectively.

Correspondingly, this definition of the subunit is applicable also toembodiments which are formed by more than two bobbins operating oneafter the other in the two machine directions S and Z. However, today,such a rope structure is not intended for current braiding machines.

The paper guide rope according to the invention may be provided in theform of a hollow rope or also in the form of a rope with a core.

EXAMPLES

The following four ropes were produced:

1) A rope according to the invention:A twisted yarn made of PA6 multifilament: 1400 dtex x3 200 T/m (inS-direction and Z-direction, respectively)This twisted yarn is impregnated.Construction of the rope: braided on a braiding machine with 16 bobbinswith the following equipment:S-direction: 8 bobbins, each with 5 S-twisted yarnsZ-direction: 4 bobbins, each with 5 Z-twisted yarns, and 4 bobbins, eachwith 4 Z-twisted yarnsHence, the subunit in the S-direction consists of 10 twisted yarns.Hence, the subunit in the Z-direction consists of 9 twisted yarns.2) A paper guide rope of conventional design with a reduced twist rateof the twisted yarn:A twisted yarn made of PA6 multifilament: 1400 dtex x6 20 T/m (inS-direction and Z-direction, respectively)This twisted yarn is impregnated.Construction of the rope: braided on a braiding machine with 16 bobbinswith the following equipment:S-direction: 8 bobbins, each with 2 S-twisted yarnsZ-direction: 6 bobbins, each with 3 Z-twisted yarns, and 2 bobbins, eachwith 2 Z-twisted yarns3) A paper guide rope of conventional design (with normal twist rate ofthe twisted yarn):A twisted yarn made of PA6 multifilament: 1400 dtex x6 80 T/m (inS-direction and Z-direction, respectively)This twisted yarn is impregnated.Construction of the rope: braided on a braiding machine with 16 bobbinswith the following equipment:S-direction: 8 bobbins, each with 2 S-twisted yarnsZ-direction: 4 bobbins, each with 3 Z-twisted yarns, and 4 bobbins, eachwith 2 Z-twisted yarns4) A rope with a monofilament reinforcementConstruction of the rope: braided on a braiding machine with 16 bobbinswith the following equipment:S-direction: 8 bobbins, each with 1 S-elementZ-direction: 8 bobbins, each with 1 Z-elementS-element: 2 S-twisted yarns (PA6 multifilament 1400 dtex x6 80 T/m)around which 16 PA-monofilaments (diameter 0.2 mm) have been braidedZ-element: 2 Z-twisted yarns (PA6 multifilament 1400 dtex x6 80 T/m)around which 16 PA-monofilaments (diameter 0.2 mm) have been braided

Measuring Method of Dry Elongation:

At a load of 1 kg, 1 m of rope is marked. Then, a load of 80 kg isapplied, the load is kept for 5 min, and subsequently the elongation isread off. Elongation in cm=elongation in %

Measuring Method of Wet Elongation:

Similar to dry elongation, but after the marking of 1 m of rope, therope is placed for 5 min in water, which is cold at 25° C.

The elongation values measured in the above ropes 1) to 4) areillustrated in the following table:

Dry elongation Wet elongation % % Rope 1) (according to the invention)2.4 4.4 Rope 2) 1.8 3.5 Rope 3) 1.9 3.5 Rope 4) 2.8 4.5

Data Regarding Lifetime and Abrasion Resistance:

The measure of the lifetime is the residual breaking load in [%] after asimulated run in a wet section of a paper-making machine. For thispurpose, a test unit consisting of 10 pulleys was developed. The ropecirculates with 800 m/min and is thereby sprayed with water(consumption: 1.6 l/h). The rope is operated at a tension of 30 kg, and,for achieving an additional abrasion effect, some of the rope pulleysare not aligned—i.e., the rope runs slightly over the rope pulley flank.

The residual strength of the ropes 1) to 4) after 24 h of thisexperiment is indicated in the following table:

24 h residual strength % Rope 1) (according to the invention) 56.7 Rope2) 24.3 Rope 3) 49.2 Rope 4) 39.5

It is clearly evident that the rope according to the invention exhibitsan improved residual strength, with the elongation properties beingsatisfactory at the same time. An optical assessment of the ropeindicates a satisfactory appearance, while, for example, rope 3 showsclearly visible stress marks.

1. A paper guide rope braided from a plurality of textile subunits,wherein each subunit contains a plurality of twisted yarns made frommultifilament yarn, characterized in that the titre of at least part ofthe twisted yarns, preferably of all the twisted yarns, is in each caseat most 5000 dtex, and that the twist rate of at least part of thetwisted yarns, preferably of all the twisted yarns, is in each case atleast 150 T/m.
 2. A paper guide rope according to claim 1, characterizedin that the rope, the subunits and the twisted yarns have noreinforcement.
 3. A paper guide rope according to claim 1, characterizedin that the twist rate of the twisted yarns is in each case 150 T/m to350 T/m, preferably 150 T/m to 250 T/m, particularly preferably 200 T/m.4. A paper guide rope according to claim 1, characterized in that thetitre of the twisted yarns is in each case 400 dtex to 5000 dtex,preferably 2500 dtex to 4500 dtex, particularly preferably 4200 dtex. 5.A paper guide rope according to claim 1, characterized in that thediameter of the rope ranges from 6 to 17 mm, preferably from 8 to 13 mm.6. A paper guide rope according to claim 1, characterized in that thetextile material of at least part of the twisted yarns consists ofpolyamide.
 7. A paper guide rope according to claim 1, characterized inthat the number of twisted yarns per subunit is at least 7.